Chirp signal filtering for digital gateway

ABSTRACT

A system and method for filtering chirp noise as it passes through a Radio over Internet Protocol (RoIP) gateway in a communication network is disclosed. Radio signals often include a short burst of chirp noise. Incoming signals are buffered and any chirp noise is detected. A chirp filter performs the filtering operation to remove chirp signal while ensuring true audio is not clipped. Without audio clipping the integrity of the audio signals are preserved.

This application claims the benefit of and is a non-provisional ofco-pending U.S. Provisional Application Ser. No. 62/957,399 filed onJan. 6, 2020, which is hereby expressly incorporated by reference in itsentirety for all purposes.

BACKGROUND

Chirp is a noise signal where frequency increases or decreases with timetypically caused by an anomalous spike in radio frequency (RF) energy.As used herein, “chirp signal” and similar terms are meant to describethese short bursts of signal, which are undesired and oftenunintentional. On the other hand, “true audio” and similar terms aremeant to describe audio signals (frequently voice) that persist longerthan chirp signals. Chirp falls under the category of non-stationarynoise having complicated pattern. In radios, chirp is typically at thebeginning of a radio grabbing the floor, but is not followed by anyaudio communication. Chirp or other anomalies can also happen at othertimes during radio transmission. Further, chirps are mono-componentsignals modulated in both amplitude and frequency, where theirinstantaneous frequency is related to the local oscillations of thephase.

Radio over Internet Protocol (RoIP) extends radio coverage to reachgreater distance when communicating with wireless networks and internet.A RoIP gateway can couple together digital communication networks withanalog or digital radio networks. RoIP can eliminate repeater linksbetween incompatible and/or distant radio networks. Remote access toradio networks across different geographical regions in addition tocross linking conventional analog radios with trunking systems arepossible.

SUMMARY

In one embodiment, the present disclosure provides a system and methodfor filtering chirp noise as it passes through a Radio over InternetProtocol (RoIP) gateway in a communication network. Radio signals ofteninclude a short burst of chirp noise that grabs the floor, but doesn'tconvey any useful audio signal. Incoming signals are buffered and anychirp noise is detected. A chirp filter performs the filtering operationto remove chirp signal while ensuring true audio is not clipped. Withoutaudio clipping the integrity of the audio signals are preserved.

In another embodiment, a radio over Internet Protocol (RoIP) gateway forcommunicatively coupling one or more radio networks and one or moredigital networks together is disclosed. The RoIP gateway includes atransceiver, a processing unit and a communication interface. Thetransceiver accepts incoming signals from a radio network. Theprocessing unit is coupled with the transceiver to process the incomingsignals. The processing unit includes a signal converter, a signaldetector, a buffer unit, and a chirp detector. The signal converter forconverts the incoming signals from the radio network into digitalsignals. The signal detector to processes the digital signals to filteraway radio network inactivity. The buffer unit stores the digitalsignals. The chirp detector to determines whether the digital signals inthe buffer unit include chirp noise. The chirp filter is coupled to thebuffer unit to filter chirp noise from the digital signals. Thecommunication interface for passing the digital signals free of chirpnoise to a digital network.

In yet another embodiment, a method of chirp signal filtering in a RoIPsystem at a first device is disclosed. In one step, a signal is detectedat an audio interface of the first device. At least a portion of thesignal is buffered by the first device responsive to detecting thesignal. Whether the signal is detected at the audio interface for athreshold duration is determined. Either: responsive to determining thesignal is detected at the audio interface for the threshold duration,causing the first device to forward the signal, including the at leastthe portion of the signal that is buffered, to a second device of theRoIP system; or, responsive to determining the signal is not detected atthe audio interface for the threshold duration, discarding the at leastthe portion of the signal that is buffered.

In still another embodiment, a method of chirp filtering for a RoIPgateway that communicatively couples one or more radio networks and oneor more digital networks together. In one step, incoming signals areaccepted from a radio network before processing the incoming signals.The incoming signals are converted from the radio network into digitalsignals. The digital signals are processed to filter away radio networkinactivity. The digital signals are stored in a memory. It is determinedwhether the digital signals in the memory include chirp noise. Whenchirp noise is determined, chirp noise is filtered from the digitalsignals, before passing the digital signals free of chirp noise to adigital network.

In the appended figures, similar components and/or features may have thesame reference label. Where the reference label is used in thespecification, the description is applicable to any one of the similarcomponents having the same reference label.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described in conjunction with the appendedfigures:

FIG. 1 depicts a simplified diagram of a RoIP system;

FIG. 2 depicts a block diagram of RoIP gateway;

FIG. 3 depicts a block diagram of chirp filter circuitry within RoIPgateway;

FIG. 4 depicts a flow-chart of buffer signal and threshold value; and

FIG. 5 depicts a flow-chart including buffer signal, threshold value andcatch-up function.

In the appended figures, similar components and/or features may have thesame reference label. Where the reference label is used in thespecification, the description is applicable to any one of the similarcomponents having the same reference label.

DETAILED DESCRIPTION

The ensuing description provides preferred exemplary embodiment(s) only,and is not intended to limit the scope, applicability or configurationof the disclosure. Rather, the ensuing description of the preferredexemplary embodiment(s) will provide those skilled in the art with anenabling description for implementing a preferred exemplary embodiment.It is understood that various changes may be made in the function andarrangement of elements without departure from the spirit and scope asset forth in the appended claims.

Embodiments of the invention(s) described herein are generally relatedto a system and method of eliminating short bursts of nuisance audio(i.e., chirp) in a Radio-over-IP (RoIP) or other radio relayenvironment. In a RoIP or other radio relay environment, the receipt ofbrief bursts of noise can result in the remote radio being keyed. Thiscan be caused by radio frequency interference or surges in radiofrequency levels. As a result the remote radio (or other communicationdevice) user is disturbed by a “chirp” of noise.

Embodiments of the invention(s) described herein are directed towardeliminating resulting short bursts of signal information withoutclipping the start of longer audio signals. To do so, embodiments maydelay the forwarding of audio to the remote party until the audio haspersisted for threshold duration, which may be configurable. This canprevent the transmission of chirp signal to the remote radio or otheraudio device until it has been confirmed as being true (non-chirp)audio. Once the presence of true audio has been confirmed, then allaudio can be forwarded—including the initial audio to ensure that thestart of the audio-burst is not lost. That is, in telecomm terminology,this can ensure that audio clipping does not occur. If audio does notpersist for threshold duration, then the audio is discarded and theremote party hears nothing.

FIG. 1 illustrates a RoIP system 100, according to an embodiment of thepresent disclosure. The RoIP system 100, two different radio networks115-1, 115-2 are communicatively coupled with a RoIP gateway 110. Inorder to communicate with each radio networks 115 the RoIP gateway 110uses donor radios 125 that can communicate with radio handsets 120 fortheir respective radio network 115 as well as with the RoIP gatewaydevice 110. The RoIP system 100 includes one or more first radiohandsets 120-1 operating on a specific radio technology is coupled witha first donor radio 125-1 through a first radio network 115-1.Similarly, one or more second radio handsets 120-2 may be operating onanother radio technology or different location is coupled with a seconddonor radio 125-2 through a second radio network 115-2. Each donor radio125 is communicatively coupled with the RoIP gateway 110 via arespective one radio port of the RoIP gateway 110 to allow interface tothe respective radio network 115.

The RoIP gateway 110 enables the first radio handset 120-1 and thesecond radio handset 120-2 to communicate further with the widercommunication network that can be geographically separated ortechnologically separated. The first radio handset 120-1 and the secondradio handset 120-2 may be operating on different radio technologies,protocols and/or encryption such that they may not be able tocommunicate directly with each other. However, RoIP gateway 110 canrelay communications between different radio networks 115. In such ascenario, the RoIP gateway 110 acts as a bridge, communicativelycoupling different radio networks 115. Each radio network 115 maycomprise any number of radio handsets 120, configured to communicatewith each other via wireless radio frequency (RF) signals. Depending onthe capacity of the RoIP gateway 110, more radio networks 115 may alsobe communicatively coupled with the RoIP system 100. This approachprovides a flexible architecture to construct a scalable RoIP system100. RoIP gateway 110 accepts the input signals from the radio handset120-1 and 120-2 which may include chirp noise originating from any pointof source either in analog or digital form.

The RoIP gateway device 110 operates to bridge communications betweenvarious different endpoints of the RoIP system 100. Arrows connectvarious components, which may be implemented using any variety ofcommunication technologies ranging from wired and/or wirelesscommunication technologies, an optical fiber network, a laserpoint-to-point, optical line of sight links using variousprotocols/standards. The RoIP system 100 may have more or fewercommunication devices, including any number of radios (e.g., donorradios 125 and/or radio handsets 120), mobile phones 155, VoIP phones145, push-to-talk (PTT) apps 150, and/or other connected devices. Radiohandsets 120 may comprise land mobile radio (LMR) handsets. PTTfunctionality could use carrier operated relay (COR) PTT functionality.The radio networks operate in a half-duplex mode, but could supportfull-duplex radios.

The RoIP gateway 110 is communicatively coupled with digitalcommunication networks via media server or session initiation protocol(SIP) private branch exchange (PBX) 160. Communications between the RoIPgateway 110 and the media server/PBX 160 may use RTP protocol to carryvoice payload, with or without accompanying SIP signaling. The mediaserver 160 is communicatively coupled with mobile phones 155 via publicswitched telephone network (PSTN) 140 and with VoIP phones 145 and PTTapplications 150 via the Internet 130. In addition to SIP, the mediaserver supports communication using hypertext transport protocol (HTTP),transmission control protocol/internet protocol (TCP/IP), and/orasynchronous transfer mode (ATM) protocols.

The RoIP gateway 110 enables radio handsets 120 to engage in audiocommunications with VoIP phones 145, mobile phones 155 and/or otherdigital communication devices. Multiple RoIP gateways 110 are possible.The RoIP gateway 110 may allow radio handsets 120 to communicate withremote radio networks coupled with another remote RoIP gateway 110communicatively coupled with the Internet 130. As such, digital andradio handsets are allowed to communicate with devices outside theirrespective digital and radio networks. The RoIP system 100 may includeadditional networks and some RoIP systems may include other RoIPgateways remote from the RoIP gateway 110, allowing other types ofnetworks to communicate over the RoIP system 100. In militaryapplications, for example, other gateways may enable packet-basedcommunication over a serial interface.

Chirp signals may be relayed through the RoIP system 100 by the RoIPgateway 110 and other endpoints in the RoIP system 100 configured toreceive and forward audio. False detection of an audio signal may resultin a SIP or other call being initiated by the media server/PBX 160.Initiation of the call is delayed until the audio has been confirmed asbeing true audio and not chirp signal.

In an embodiment, the RoIP gateway 110 may comprise a transceiver withwhich it communicates to a particular donor radio 125-1. If the RoIPgateway 110 receives a signal on the transceiver 204 used to communicatewith donor radio 125-1, the RoIP gateway 110 may digitize and forwardthe signal to the mobile device executing PTT apps 150, via the mediaserver or SIP PBX 160 and internet 130. If the signal received by theRoIP gateway 110 at the transceiver is a short audio burst from thedonor radio 125-1, or even a spike in amplitude due to non-audio energy(noise), it will be digitized and forwarded to the PTT apps 150,resulting in an indication of audio beep with no accompanying trueaudio. Thus, the propagation of these chirp signals throughout the RoIPsystem 100 can be a nuisance to many communication devices within theRoIP system 100, negatively impacting user experience and reducing theoverall effectiveness of communications within the RoIP system 100.These sudden burst in a signal chirp noise may be generated at anycommunication devices in the RoIP system 100 and typically by analogradio handsets 120. Chirp filtering process can eliminate these noisesignals received at the RoIP gateway device 110.

FIG. 2 illustrates one embodiment of the RoIP gateway 110 that bridgesthe radio and digital networks. At one side, a transceiver 204receives/transmits radio signals of the donor radios 125. On the otherside, signals received/sent with the digital networks are processed by aSIP controller 212 for the SIP PBX 160. The transceiver 204 iscommunicatively coupled to a baseband processor 208, which digitallyprocesses the signals which may include the chirp noise generated at anycommunication devices of the RoIP network 100. Further, basebandprocessor 208 is communicatively coupled to a SIP controller 212 whichin turn is coupled with the digital networks via SIP PBX 160 tocommunicatively couple the radio network with one or more digitalnetworks.

The baseband processor 208 can buffer a signal received at the audiointerface and, if the signal has persisted for threshold duration,forward the true signal to the SIP controller 212. Otherwise, thebaseband processor 208 can discard the signal as chirp signal. The SIPcontroller 212 sends/receives communication for the SIP PBX 160.

COR signaling can be used to indicate when true audio is beingcommunicated via an audio channel (e.g., an analog audio interface ofthe RoIP gateway device 110) to filter out chirp signals for radionetworks 115 that support COR. For radio handsets 120 without CORsignaling, the chirp can be filtered.

When the analog audio interface of the RoIP gateway 110 is beingoperated in a “voice activity detection” (audio detection) mode, inwhich the RoIP gateway device 110 forwards audio detected at the donorradio, via the analog audio interface. Operation of the RoIP gateway 110in the voice activity detection mode may be based on user preferences,capabilities of the donor radio 125, and/or other factors.

FIG. 3 illustrates a baseband processor 208 for processing the trueaudio and chirp signals along with noise received from the transceiver204 in one embodiment. A signal converter 304 accepts the output signalsof the transceiver 204. Signal converter 304 converts the input signalsreceived from the transceiver 204 into digital form using an analog todigital converter (ADC). The signal converter 304 is communicativelycoupled with a signal detector 308 to identify whether the outputsignals from the signal converter 304 includes any active signal fromthe radio network (i.e., active signal could include chirp signal ortrue audio) or just noise that would be removed.

The signal detector 308 is communicatively coupled with a buffer 312that stores digital signal, for example, in a first in/first out (FIFO)configuration where an input pointer places digital samples into thebuffer and an output pointer indicates the next digital sample to removefrom the buffer 312. Generally, the input pointer and output pointermove through the buffer 312 synchronously to output digital signal asfast as it is input.

The buffer 312 is coupled with a chirp detector 316 to ascertain whetherthe buffered signals include any chirp noise or other sudden burstcomponent in the digital signals. In this embodiment, chirp signal isdetected when the buffer 312 only fills to a given threshold before theradio signal releases the floor. For example, a 200 ms or less digitalsignal is flushed from the buffer 312 upon recognition by the chirpdetector of the chirp signal. A chirp filter 320 flushes the buffer byincrementing the output pointer by the length of the digital signal thatis less than the threshold. For example, a 50 ms RF burst of energymight fill the buffer 312 by incrementing the input pointer with eachsample for the digital signal before releasing the channel by a radiohandset 120. The output pointer runs a maximum of 200 ms in bufferdelay. Once the threshold is not met, the chirp filter 312 incrementsthe output pointer over the 50 ms RF burst to effectively erase it sothat it is not coupled to the SIP controller 212.

The chirp duration threshold can be other values in differentembodiments, for example 10 ms, 25 ms, 50 ms, 75 ms, 100 ms, 150 ms, 250ms, 300 ms, or more. For different radio handsets 120 or radio networks115, a different threshold could be used, for example, the first radionetwork 115-1 could have a 150 ms threshold and the second radio network115-2 could have a 250 ms threshold. Other embodiments could interrogatethe buffer 312 with the chirp detector 316 using machine learning and/orartificial intelligence algorithms to more quickly or definitivelyidentify chirp signal or other sudden burst components that are not trueaudio. Different specific radios may have repeating patterns of chirpsignal that could also be recognized by the chirp detector by keepingindividual profiles on each radio, model of radio, radio type, etc.

The buffer 312 along with other digital processing of the basebandprocessor 208 introduces delay or latency. For example, a 200 ms chirpthreshold results in that same amount of additional delay through thebaseband processor 208. The latency produces a lag in communication thatcan make it awkward for those that might respond. Optionally, thisembodiment uses catch-up circuitry to reduce that delay during a givenradio communication. The catch up circuitry 324 speeds-up the signalspooled from the buffer to overcome any delay added during chirpfiltering. For example, a 10 second true audio transmission may startwith 200 ms of buffer delay that results in the first 5 seconds beingspooled out quicker such that the remaining 5 second true audio has nobuffer delay. Sped-up signal can distort the true audio and the catch-upcircuitry 324 can auto-tune the pitch back closer to the true audio.

Although this embodiment uses a circular buffer that allows skippingdigital signal by manipulation of the output pointer, other embodimentscould use a micro controller to perform the filtering and catch-upwithout a dedicated buffer in other embodiments. Digital signal could bestored in standard memory for chirp detection/filtering and catch-up.Additionally, the microcontroller could perform other filtering, signalencryption and digital encoding. Some microcontrollers also contain ADCcircuitry and other functions in a single-chip baseband processor.

FIG. 4 is a flow diagram illustrating the functions a RoIP gatewaydevice 110 may perform for chirp signal filtering, according to anembodiment. The RoIP gateway 110 may perform the illustrated functionsfor each digital or radio interface that receives digital signal forcommunication across the RoIP system 100.

The method may begin at block 410, where the RoIP gateway device 110operates in a signal detection mode performed by the signal detector308. In some embodiments, the RoIP gateway device 110 may simply monitorincoming signal from a donor radio 125 to determine if it containssignals having amplitude above a certain threshold level of audio.Incoming signals made not be due solely to incoming true audio from anattached donor radio 125, but may be due to interference, for example,chirp signal. Once a digital signal is detected above the thresholdlevel by the baseband processor 208, it is stored in the buffer 312, asindicated at block 420.

The detection of a signal can vary, depending on desired functionality.In some embodiments, the incoming analog signal information from theanalog audio interface can be converted to digital data using an ADC,packetized into data packets, and sent to a signal detector 308 (e.g., amicrocontroller or microprocessor) to determine whether a digital signalis present. In some embodiments, for example, each data packet includessignal information for 20 ms of incoming signal. (At a sample rate of 16kHz, for instance, each data packet would include 320 samples of signaldata.) Alternative embodiments may have data packets containing largeror smaller amounts of audio data—including different sampling rates(larger or smaller than 16 kHz) and/or different durations of audio data(larger or smaller than 20 ms in length). According to some embodiments,the determination of whether a signal is present in the data packet maycomprise determining whether a threshold number of samples (e.g., one ormore) of signal data, and/or a mean or average value of samples ofsignal data have an amplitude greater than a threshold amount (e.g., 0or greater, but this may be dependent on sampling bit depth).

In some embodiments, a determination of whether a signal is detected mayfurther comprise the determination of whether a specific type of signal(e.g., voice) is detected. For example, in some embodiments, theinformation in each data packet may be analyzed to determine whether avoice-range frequency (e.g., a frequency within the range of 300 to 3400kHz) is detected by the signal detector 308 and/or chirp detector 316.

The filtering of chirp signals can be implemented by determining whetherthe detected signal has met a duration threshold. That is, as shown atblock 425, embodiments may determine whether to forward the bufferedsignal data if the detected signal being buffered has met a thresholdlength of time. The threshold duration may vary, depending on desiredfunctionality. Moreover, this threshold duration may be configurable byan operator of the RoIP gateway device 110.

Generally speaking, the threshold duration may be configured as aminimum amount of time for a true audio signal, which may be on theorder of tens of milliseconds, for example. That said, in someapplications, a user may want to set a relatively long thresholdduration (e.g., 100 ms or more). Accordingly, embodiments of a RoIPgateway device 110 may utilize a memory with sufficient capacity toprovide for such relatively long threshold durations at the sample ratefor the digital signal.

In embodiments in which signal data is packetized, the configurabilityof the threshold duration may be a function of data packet length. Morespecifically, the threshold duration may be N×packet length, where N isthe number of successive data packets in which a signal is detected. Inthe example where each data packet includes 20 ms of signal data, forexample, the threshold duration may be in multiples of 20 ms (20, 40,60, 80, or 100 ms, or more). Again, this threshold may be set by anoperator of the RoIP gateway device 110.

If the signal does not last the threshold duration (e.g., signal is notdetected for N successive data packets), the buffered signal can then bediscarded, at block 430, by the chirp filter and the RoIP gateway device110 can again enter the signal detection mode at block 410.

On the other hand, if the signal meets the threshold duration, the RoIPgateway device 110 can then forward the buffered signal 435 to the SIPcontroller 212. Here, the RoIP gateway device 110 can prevent audioclipping by continually buffering incoming audio detected at the analogaudio interface and forwarding the buffered audio, as shown at block440. Thus, the forwarded audio signal may have any length, and may bedelayed only by the length of the threshold duration. Because thethreshold duration may be only a fraction of a second, this delay inaudio forwarding may be insignificant (and even undetectable by users).

In some embodiments, the value of the threshold duration may beautomatically adjusted over time, to accommodate the particular audio(and/or RF) environment of the donor radio 125 and the radio network 115from which the donor radio 125 receives audio communication, and changesthereto. In some embodiments, the value of the threshold duration may begiven an initial value (e.g., a default setting set by the manufactureror a value selected by a RoIP gateway device operator) when the donorradio 125 is first connected with the RoIP gateway device 110. Overtime, the RoIP gateway device 110 can optimize this value byautomatically “tuning” it based on an analysis of signal data. Differentspecific radios, radio types, radio networks, may have differentthreshold durations that are different.

For example, the value of the threshold duration may be given an initialvalue of 100 ms (relatively long to increase the amount of chirp signalfiltering). However, after analyzing discarded buffered signal data(e.g., in real time, over the course of a period of time of seconds,minutes, hours, etc.) the RoIP gateway device 110 may identify thatdiscarded buffered signal data rarely (if ever) exceeds 60 ms. (Putdifferently, if a signal is detected for three 20 ms packets in a row,the signal will virtually always persist for longer than the 100 msthreshold duration.) The RoIP gateway device 110 can then lower thevalue of the threshold duration to 60 ms to reduce the delay inforwarding the buffered signal while maintaining optimal chirp signalfiltering.

On the other hand, the RoIP gateway device 110 may analyze the forwardedsignal to determine whether chirp signals are being forwarded (e.g.,signals that exceed the threshold duration but do not persist longerthan a relatively short time for true audio—such as 100 ms), then theRoIP gateway 110 can increase the value of the threshold duration toincrease the amount of chirp signal filtering. Machine learning andartificial intelligence can be used to increase or decrease thethreshold(s) over time for the various radios, latencies, circuitvariations, time lags due to geographies, etc.

By analyzing signal data on an ongoing basis to determine whether thevalue of the threshold duration should be increased or decreased, theRoIP gateway device 110 can ensure the threshold duration value remainsoptimized despite changes in the audio and/or RF environment over time.As noted, an operator of the RoIP gateway 110 may choose to enable ordisable automatic adjustment of the value of the threshold duration.Moreover, in some embodiments, the amount of data analyzed by the RoIPgateway 110 (e.g., seconds, minutes, hours, etc.) may also beconfigurable.

FIG. 5 is a flow chart showing another embodiment of how the RoIPgateway 110 functions to remove chirp signal in favor of true audio withcatch-up circuitry to speed-up the digital signal when there is trueaudio. In comparison with FIG. 4, a block 504 is added between blocks425 and 435 that performs the accelerated playback of the catch-upcircuitry 324. This could be as simple as incrementing the outputpointer of the buffer 312 more quickly or dropping some digital samplesaltogether. Or, more sophisticated algorithms for speeding playback ofaudio without introducing distortion could be used.

A number of variations and modifications of the disclosed embodimentscan also be used. For example, chirp typically comes from the analogradios, but in some embodiments chirp can come from the digitalhandsets. Similar chirp filtering can be used for the signals thatoriginate from the digital networks in the RoIP gateway.

Specific details are given in the above description to provide athorough understanding of the embodiments. However, it is understoodthat the embodiments may be practiced without these specific details.For example, circuits may be shown in block diagrams in order not toobscure the embodiments in unnecessary detail. In other instances,well-known circuits, processes, algorithms, structures, and techniquesmay be shown without unnecessary detail in order to avoid obscuring theembodiments.

Also, it is noted that the embodiments may be described as a processwhich is depicted as a flowchart, a flow diagram, a swim diagram, a dataflow diagram, a structure diagram, or a block diagram. Although adepiction may describe the operations as a sequential process, many ofthe operations can be performed in parallel or concurrently. Inaddition, the order of the operations may be re-arranged. A process isterminated when its operations are completed, but could have additionalsteps not included in the figure. A process may correspond to a method,a function, a procedure, a subroutine, a subprogram, etc. When a processcorresponds to a function, its termination corresponds to a return ofthe function to the calling function or the main function.

For a firmware and/or software implementation, the methodologies may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. Any machine-readable mediumtangibly embodying instructions may be used in implementing themethodologies described herein. For example, software codes may bestored in a memory. Memory may be implemented within the processor orexternal to the processor. As used herein the term “memory” refers toany type of long term, short term, volatile, nonvolatile, or otherstorage medium and is not to be limited to any particular type of memoryor number of memories, or type of media upon which memory is stored.

In the embodiments described above, for the purposes of illustration,processes may have been described in a particular order. It should beappreciated that in alternate embodiments, the methods may be performedin a different order than that described. It should also be appreciatedthat the methods and/or system components described above may beperformed by hardware and/or software components (including integratedcircuits, processing units, and the like), or may be embodied insequences of machine-readable, or computer-readable, instructions, whichmay be used to cause a machine, such as a general-purpose orspecial-purpose processor or logic circuits programmed with theinstructions to perform the methods. Moreover, as disclosed herein, theterm “storage medium” may represent one or more memories for storingdata, including read only memory (ROM), random access memory (RAM),magnetic RAM, core memory, magnetic disk storage mediums, opticalstorage mediums, flash memory devices and/or other machine readablemediums for storing information. The term “machine-readable medium”includes, but is not limited to portable or fixed storage devices,optical storage devices, and/or various other storage mediums capable ofstoring that contain or carry instruction(s) and/or data. Thesemachine-readable instructions may be stored on one or moremachine-readable mediums, such as CD-ROMs or other type of opticaldisks, solid-state drives, tape cartridges, ROMs, RAMs, EPROMs, EEPROMs,magnetic or optical cards, flash memory, or other types ofmachine-readable mediums suitable for storing electronic instructions.Alternatively, the methods may be performed by a combination of hardwareand software.

Implementation of the techniques, blocks, steps and means describedabove may be done in various ways. For example, these techniques,blocks, steps and means may be implemented in hardware, software, or acombination thereof. For a hardware implementation, the processing unitsmay be implemented within one or more application specific integratedcircuits (ASICs), digital signal processors (DSPs), digital signalprocessing devices (DSPDs), programmable logic devices (PLDs), fieldprogrammable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described above, and/or a combination thereof.

Furthermore, embodiments may be implemented by hardware, software,scripting languages, firmware, middleware, microcode, hardwaredescription languages, and/or any combination thereof. When implementedin software, firmware, middleware, scripting language, and/or microcode,the program code or code segments to perform the necessary tasks may bestored in a machine readable medium such as a storage medium. A codesegment or machine-executable instruction may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a script, a class, or any combination of instructions,data structures, and/or program statements. A code segment may becoupled to another code segment or a hardware circuit by passing and/orreceiving information, data, arguments, parameters, and/or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

The methods, systems, devices, graphs, and tables discussed herein areexamples. Various configurations may omit, substitute, or add variousprocedures or components as appropriate. For instance, in alternativeconfigurations, the methods may be performed in an order different fromthat described, and/or various stages may be added, omitted, and/orcombined. Also, features described with respect to certainconfigurations may be combined in various other configurations.Different aspects and elements of the configurations may be combined ina similar manner. Also, technology evolves and, thus, many of theelements are examples and do not limit the scope of the disclosure orclaims. Additionally, the techniques discussed herein may providediffering results with different types of context awareness classifiers.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly or conventionally understood. As usedherein, the articles “a” and “an” refer to one or to more than one(i.e., to at least one) of the grammatical object of the article. By wayof example, “an element” means one element or more than one element.“About” and/or “approximately” as used herein when referring to ameasurable value such as an amount, a temporal duration, and the like,encompasses variations of ±20% or ±10%, ±5%, or +0.1% from the specifiedvalue, as such variations are appropriate to in the context of thesystems, devices, circuits, methods, and other implementations describedherein. “Substantially” as used herein when referring to a measurablevalue such as an amount, a temporal duration, a physical attribute (suchas frequency), and the like, also encompasses variations of ±20% or±10%, ±5%, or +0.1% from the specified value, as such variations areappropriate to in the context of the systems, devices, circuits,methods, and other implementations described herein.

As used herein, including in the claims, “and” as used in a list ofitems prefaced by “at least one of” or “one or more of” indicates thatany combination of the listed items may be used. For example, a list of“at least one of A, B, and C” includes any of the combinations A or B orC or AB or AC or BC and/or ABC (i.e., A and B and C). Furthermore, tothe extent more than one occurrence or use of the items A, B, or C ispossible, multiple uses of A, B, and/or C may form part of thecontemplated combinations. For example, a list of “at least one of A, B,and C” may also include AA, AAB, AAA, BB, etc.

While illustrative and presently preferred embodiments of the disclosedsystems, methods, and machine-readable media have been described indetail herein, it is to be understood that the inventive concepts may beotherwise variously embodied and employed, and that the appended claimsare intended to be construed to include such variations, except aslimited by the prior art. While the principles of the disclosure havebeen described above in connection with specific apparatuses andmethods, it is to be clearly understood that this description is madeonly by way of example and not as limitation on the scope of thedisclosure.

What is claimed is:
 1. A radio over Internet Protocol (RoIP) gateway forcommunicatively coupling one or more radio networks and one or moredigital networks together, the RoIP gateway comprising: a transceiver toaccept incoming signals from a radio network; a processing unit coupledwith the transceiver to process the incoming signals, the processingunit comprising: a signal converter for converting the incoming signalsfrom the radio network into digital signals, a signal detector toprocess the digital signals to filter away radio network inactivity, abuffer unit for storing the digital signals, a chirp detector todetermine whether the digital signals in the buffer unit include chirpnoise, and a chirp filter coupled to the buffer unit to filter chirpnoise from the digital signals; and a communication interface forpassing the digital signals that are free of chirp noise to a digitalnetwork.
 2. The RoIP gateway for communicatively coupling one or moreradio networks and one or more digital networks together as recited inclaim 1, wherein the digital network use Session Initiation Protocol(SIP), Hypertext Transport Protocol (HTTP), Transmission ControlProtocol/Internet Protocol (TCP/IP), and/or Asynchronous Transfer Mode(ATM) protocols in a unicast or multicast configuration.
 3. The RoIPgateway for communicatively coupling one or more radio networks and oneor more digital networks together as recited in claim 1, wherein thetransceiver operates in a half-duplex mode.
 4. The RoIP gateway forcommunicatively coupling one or more radio networks and one or moredigital networks together as recited in claim 1, wherein thecommunication interface provides communication with Internet Protocol(IP) enabled apparatus coupled with the communication interface.
 5. TheRoIP gateway for communicatively coupling one or more radio networks andone or more digital networks together as recited in claim 1, wherein thedigital networks comprising one or more of a wired network, an opticalfiber network, a laser point-to-point, optical line of sight, a wirelessnetwork.
 6. The RoIP gateway for communicatively coupling one or moreradio networks and one or more digital networks together as recited inclaim 1, wherein: the transceiver to accepts incoming signals from asecond radio network, and the radio network and second radio networkcannot directly communicate with each other without the RoIP gateway. 7.The RoIP gateway for communicatively coupling one or more radio networksand one or more digital networks together as recited in claim 1, whereinthe signal detector only forwards the digital signals that persist forthreshold duration.
 8. The RoIP gateway for communicatively coupling oneor more radio networks and one or more digital networks together asrecited in claim 1, wherein the chirp detector communicates with thebuffer unit to process the digital signals to detect chirp signal andinstruct the chirp filter to filter the chirp signal.
 9. The RoIPgateway for communicatively coupling one or more radio networks and oneor more digital networks together as recited in claim 1, wherein thechirp filter avoids clipping digital signals that are free of chirpnoise to preserve audio signal integrity.
 10. The RoIP gateway forcommunicatively coupling one or more radio networks and one or moredigital networks together as recited in claim 1, wherein the processingunit further comprises catch-up circuitry accelerate a read rate of thebuffer.
 11. A method of chirp signal filtering in a RoIP system at afirst device, the method comprising: detecting a signal at an audiointerface of the first device; responsive to detecting the signal,buffering at least a portion of the signal by the first device;determining whether the signal is detected at the audio interface for athreshold duration; and either: responsive to determining the signal isdetected at the audio interface for the threshold duration, causing thefirst device to forward the signal, including the at least the portionof the signal that is buffered, to a second device of the RoIP system;or responsive to determining the signal is not detected at the audiointerface for the threshold duration, discarding the at least theportion of the signal that is buffered.
 12. The method of chirp signalfiltering in the RoIP system at the first device claim 11, whereindetecting the signal at the audio interface comprises analyzing one ormore successive data packets of signal data.
 13. The method of chirpsignal filtering in the RoIP system at the first device claim 12,wherein detecting the signal at the audio interface further comprisesdetermining a threshold number of audio samples within a data packet ofthe one or more successive data packets have a threshold value.
 14. Themethod of chirp signal filtering in the RoIP system at the first deviceclaim 12, wherein detecting the signal at the audio interface furthercomprises determining a data packet of the one or more successive datapackets comprises a voice frequency.
 15. The method of chirp signalfiltering in the RoIP system at the first device claim 12, whereindetermining whether the signal is detected at the audio interface forthe threshold duration comprises determining that audio is present in athreshold number of successive data packets of the one or moresuccessive data packets.
 16. The method of chirp signal filtering in theRoIP system at the first device claim 11, further comprising: analyzingthe signal; and adjusting a value of the threshold duration based atleast in part on the analyzing the signal.
 17. The method of chirpsignal filtering in the RoIP system at the first device claim 16,wherein the analyzing the signal and adjusting the value of thethreshold duration are based at least in part on user input.
 18. Amethod of chirp filtering for a RoIP gateway that communicativelycouples one or more radio networks and one or more digital networkstogether, the method comprising: accepting incoming signals from a radionetwork; processing the incoming signals; converting the incomingsignals from the radio network into digital signals; processing thedigital signals to filter away radio network inactivity; storing thedigital signals in a memory; determining whether the digital signals inthe memory include chirp noise; when chirp noise is determined:filtering chirp noise from the digital signals, and passing the digitalsignals free of chirp noise to a digital network.
 19. The method ofchirp filtering for the RoIP gateway that communicatively couples one ormore radio networks and one or more digital networks together as recitedin claim 17, the method further comprising accelerating playback of thedigital signals after filtering chirp noise whereby delay between realtime and the playback is reduced.
 20. The method of chirp filtering forthe RoIP gateway that communicatively couples one or more radio networksand one or more digital networks together as recited in claim 17,wherein the memory is a circular buffer.